The invention is based on an apparatus for injecting a fuel-gas mixture into an internal combustion engine as defined hereinafter. German Patent Disclosure Document DE-OS 36 09 798 already discloses an apparatus for injecting a fuel-gas mixture in which a recessed longitudinal bore of a valve holder fits around a fuel injection valve. Upstream of one injection end of the fuel injection valve, a mixing chamber is embodied in the valve holder, communicating upstream, via an annular gas gap formed between the injection end and the longitudinal bore, with an annular gas conduit that communicates with a gas source. However, this apparatus has the disadvantage that the size of the annular gas gap and the quality of centering of the fuel injection valve in the longitudinal bore of the valve holder are dependent on the tolerances in terms of length and shape of the fuel injection valve and of the longitudinal bore of the valve holder.
Because the guidance of the fuel injection valve in the longitudinal bore is at a pronounced distance from the injection end, the danger exists of canting and/or offset of the center axis of the fuel injection valve in the longitudinal bore of the valve holder and thus of an asymmetric embodiment of the annular gas gap and asymmetric injection of the fuel into the mixing chamber. Neither central injection of the fuel and thus the formation of a predominantly homogeneous fuel-gas mixture nor a requisite exact embodiment of the defined annular gas gap for the sake of precisely metered gas delivery is assured with any likelihood.